Stability of conducting polyester/polypyrrole fabrics in different pH solutions. Chemical and electrochemical characterization

The stability of conducting fabrics of polyester (PES) covered with polypyrrole/anthraquinone sulfonic acid (AQSA) has been tested in different pH solutions (1, 7, 13) and after washing tests. It is important to determine the stability of the counter-ion in the polymer matrix, since its loss causes the decrease of the conducting properties of the fabrics. X-ray photoelectron spectroscopy (XPS) studies were done to quantify the amount of counter-ion in the polymer and to obtain the doping level (Nδ+/N). Surface resistivity changes after the different tests were measured by electrochemical impedance spectroscopy (EIS). An increase in the solution pH caused a decrease of the doping level (Nδ+/N), the release of part of the counter-ions and an increase in the surface resistivity. Cyclic voltammetry (CV) measurements showed a gradual loss of electroactivity as pH increased. The influence of the scan rate on the characterization of conducting fabrics has been also demonstrated by CV. Lower scan rates produce a more characteristic response than higher ones. Scanning electrochemical microscopy (SECM) measurements showed a loss of electroactivity when the sample was tested in the pH 13 solution, although the material continued being electroactive.